"It is not enough to declare war on what one deems terrorism without giving a precise and exact definition," Lahoud said in a meeting with foreign diplomats on Monday.
He also said it was unacceptable for states to offer their own definition in the absence of an international interpretation, alluding to the United States, which had accused Lebanon of harbouring terrorists.
"It is likewise unacceptable for the world's big powers to impose their concepts and definitions of this term on weaker countries," added the president.
US Defence Secretary Donald Rumsfeld has reportedly raised the possibility of sending special forces to the Syrian-controlled Bekaa Valley in eastern Lebanon "to apprehend terrorists."
Washington regards the Lebanese resistance group Hizb Allah, which spearheaded efforts to oust Israeli forces from south Lebanon following a 22-year occupation in May 2000, as a "terrorist" group. The group rejects the accusation.
The Lebanese president also criticised "the application of double standards" in the Middle East.
"Israel occupies Arab territory, kills and massacres, and increases the number of its settlements... possesses weapons of mass destruction and rejects all resolutions drawn up under international law.
"And, moreover, it has the audacity to claim it is fighting what it calls Palestinian terror, while the international community says nothing," said Lahoud.
Syria, the main power-broker in Lebanon, called last year for an international conference on terrorism to define the term.